What Sweat Is Made Of

In order to know what your body loses when it sweats it is important to first understand what sweat is made of. There are two types of sweat glands in the human body: eccrine and apocrine glands. Both produce sweat with a different chemical composition. Eccrine glands tend to produce sweat that is clear, odorless, and composed of primarily water. The sweat from eccrine glands also contains waste products from the blood like sodium chloride, urea, uric acid, proteins and immunoglobulins. Apocrine glands are only located on specific parts of the body, like the groin and armpit, and they produce sweat that is thicker, yellowish, and which has an odor. The sweat produced by apocrine glands also contains proteins and fatty acids. Typically, when people worry about losing nutrients from sweat they are concerned with the sweat that is being produced by the eccrine glands. Eccrine glands are located all over the body and they are the sweat glands that are activated by an increase in body temperature.[1]

The Biggest Things Your Body Loses When You Sweat

The biggest thing the body loses when it sweats is water. In fact, over 99% of sweat is made up of water.[2] When someone is sweating excessively the biggest thing they need to worry about is dehydration due to water loss. This most often happens due to a combination of high environmental temperatures, exercise, and the type of clothing a person is wearing which are factors related to why humans sweat. Excessive sweating that leads to dehydration can also lead to the loss of necessary electrolytes and a low plasma level in blood.[3] Electrolytes are essentially salts like potassium, calcium, magnesium, and sodium chloride (table salt) that the body needs to maintain water movement in and out of cells and to spark nerve impulses throughout the body. This is also why people are often left with a salty taste on their skin when the sweat a lot. To battle electrolyte imbalances from sweat loss people are encouraged the drink plenty of fluids that contain electrolytes (think Pedialyte or Gatorade) to replenish their body’s supply. One study found that men exposed to temperatures of 100 degrees or higher for a period of 7.5 hours lost relatively high concentrations of of not only potassium, magnesium, and sodium, but also iron. This suggests that mineral imbalances from sweat loss are more extensive than researchers previously thought.[4] Electrolytes are certain types of minerals that the body loses in sweat, but what about vitamins?

While electrolytes are the most well-known micronutrients affected by sweat loss, vitamin concentrations within the body can also be impacted. Researchers looking at the effects of excessive sweat loss are generally most interested in water soluble vitamins, as they are most likely to be carried in sweat. One study of factory workers exposed to high temperatures found that they had especially high losses of vitamin C related to sweat loss. Other vitamins that the study looked at, but that appeared to be less impacted by sweat loss, included B1 and B2. People who are experiencing excessive sweat loss, for whatever reason, should strive to combat potential deficiencies of micronutrients by including more of them in their diet. Micronutrients (other than vitamin D) cannot be made by the body, so they need to be supplied by diet.[5]

Hyperhidrosis and Sweat Loss

While hyperhidrosis, a condition that causes a person to sweat excessively, is distressing and physically uncomfortable, it is generally not dangerous. People with hyperhidrosis often sweat much more than is needed by the body, but typically not enough to deplete nutrients and cause a physiological crisis.[6] However, it wouldn’t be a bad idea for people with hyperhidrosis to regularly replenish micronutrients in an effort to maintain optimal health.

Sources
  1. Huddle, J. R. (2014). Hyperhidrosis: Causes, Treatment Options and Outcomes. New York, NY: Nova Science.
  2. Festa, J. (2015, July/August). 20 Things You Didn't Know About... Sweat. Discover.
  3. Popkin, B. M., D'anci, K. D., & Rosenburg, I. H. (2010). Water, Hydration and Health. Nutr Rev.,68(8), 439-458. doi:10.1111/j.1753-4887.2010.00304.x
  4. Consolazio, C. F., Matoush, L. O., Nelson, R. A., Harding, R. S., & Canham, J. E. (1969). Excretion of Sodium, Potassium, Magnesium and Iron in Human Sweat and the Relation of Each to Balance and Requirements. The Journal of Nutrition, 79(4), 407-415. Retrieved February 28, 2019, from https://doi.org/10.1093/jn/79.4.407.
  5. Tang, Y. M., Wang, D., Li, J., Li, X., Liu, N., Liu, W., & Li, Y. (2016). Relationships between micronutrient losses in sweat and blood pressure among heat-exposed steelworkers. Ind Health,54(3), 215-223. doi:10.2486/indhealth.2014-0225
  6. Pariser, D. M. (2014). Hyperhidrosis (4th ed., Vol. 32). Philadelphia, PA: Elsevier.